Facebook officials sent an invitation Tuesday to members of the media, asking the press to come to the social media giant’s Menlo Park, California headquarters on Jan. 15 to “see what we’re building.”

Tech journalists were quick to start speculating about what the pow wow at Mark Zuckerberg’s HQ could mean, noting that Facebook officials don’t frequently hold big events at the headquarters. Speculation also immediately started around whether this could be an announcement that Facebook is preparing to launch a mobile device of its own — the ever-elusive Facebook Phone.

In the past, Facebook media events such as this have resulted in reveals of details about the Facebook Open Graph and how businesses could utilize it to optimize their advertising spend, as well as the debut in 2011 of Facebook video chat.

Speculation about the Facebook phone was further fueled by rumors that started flying Tuesday that Apple — a company not in attendance at the major Consumer Electronics Show in Las Vegas, this week — is planning to release a low-cost iPhone device.

It’s tough to guess what Facebook’s announcement could be. If I were to place odds on a Facebook phone of some type being announced next week, I would call it 20:1 odds — that is, I don’t think it’s very likely. While having its own mobile device could have many advantages for Facebook, those advantages would likely only be realized if the phone were both executed perfectly and it were widely adopted by the market. The mobile phone market is simply saturated with many different options and I imagine it would be difficult for a Facebook phone to break through and make noise on its own.

What might be more likely, in the mobile phone arena, and I’ll set 10:1 odds on it happening, is a partnership between Facebook and some existing mobile phone manufacturer, to release a phone with enhanced Facebook capabilities. But even this idea is a stretch, as I don’t see a Facebook-themed Android OS in the cards ever, and Facebook alterations to iOS are even more unlikely.

What do you think are the best possibilities for Facebook’s announcement on Jan. 15? Better yet, what is something that Facebook could announce that would wow you as a Facebook user?